JP4411250B2 - Method for producing tea beverage - Google Patents

Description

  The present invention relates to a method for producing a tea beverage, and more particularly to a method for producing a tea beverage having an excellent aroma.

  In the manufacturing process of tea beverages, how to suppress deterioration due to oxidation of tea extract is an important issue. Thus, various methods for blocking oxygen have been considered. For example, a method of performing extraction using deaerated water has been proposed. However, this method has a problem that a stable effect cannot be obtained because oxygen can be redissolved in the steps after extraction. In addition, when oxygen is forcibly degassed from the extracted water, there is a problem that the jumping effect of tea leaves is lost.

  As another method, Patent Document 1 describes a method of degassing with carbon dioxide gas. However, since carbon dioxide has high solubility in an aqueous solution, it is difficult to completely remove it from the solution. If the degassing of carbon dioxide is insufficient, the sourness due to carbon dioxide remains and affects the flavor. Further, in the process of degassing the carbon dioxide gas, there is a problem that the fragrance is emitted from the solution and the fragrance as a tea beverage is weakened.

Patent Document 2 describes a method for producing a beverage under a nitrogen atmosphere. However, this method only prevents the dissolution of oxygen in the solution, and cannot reduce the oxygen concentration originally present in the solution. Patent Document 3 discloses that in the production of dairy beverages, the generation of dimethyl disulfide generated by heating is reduced by substituting with an inert gas such as nitrogen so that the dissolved oxygen in the liquid is 5 ppm or less. A method is described. However, since tea beverages tend to change in color and aroma, it has been difficult to produce products that can be provided as tea beverages by a method that suppresses oxidative degradation by simply mixing nitrogen.
Japanese Patent No. 3452805 JP2002-211676 Japanese Patent No. 3083798

  In view of the above problems, an object of the present invention is to provide a method for producing a tea beverage that suppresses flavor loss due to oxidative degradation of a tea beverage, is stable in quality, and has an excellent flavor.

  According to the present invention, extracting tea leaves, adjusting the obtained tea extract to pH 5.0 to 6.0, mixing nitrogen into the tea extract, and applying a negative pressure of 0.01 MPa or more, Following the step of applying the negative pressure, the tea extract is maintained at a pressure below atmospheric pressure for 30 seconds to 20 minutes for stabilization, and the tea extract during or after the stabilization step. And a step of adjusting the pH to 5.5 to 6.5. Here, the tea extract whose pH is adjusted after the stabilization step preferably has a dissolved oxygen content of 1 ppm or less. Moreover, it is preferable that the said stabilization process is performed under atmospheric pressure.

  Furthermore, the process which sterilizes the said tea drink and fills a sealed container is comprised. Preferably, the filling step is performed under aseptic conditions. The sealed container is preferably high barrier PET.

  According to the present invention, it is possible to suppress oxidative deterioration in the production process of a tea beverage, and it is possible to produce a packaged tea beverage that is stable in quality and has an excellent flavor and color.

  The present invention is a method for producing a tea beverage excellent in flavor and color, preferably a containerized tea beverage. The inventors pay attention to the fact that the tea extract is accelerated by heat, and prior to the sterilization process that is most susceptible to the influence of dissolved oxygen due to the most heat load in the production process, the dissolved oxygen concentration in the liquid is determined. By reducing it, it was possible to provide a tea beverage with excellent flavor.

  In the present invention, a method of mixing nitrogen is used as a method of reducing the dissolved oxygen concentration in the liquid. However, the nature of green tea beverages is likely to change, and there is a problem that the color tone and aroma deteriorate when this method is used. The present inventors have clarified that the influence of this nitrogen mixing is caused by an increase in pH, and succeeded in suppressing the influence of nitrogen by controlling the pH.

  In the method for producing a tea beverage of the present invention, tea leaves are first extracted to prepare a tea extract. The extraction method of tea leaves may be performed by a well-known method, and conditions such as extraction temperature and extraction time may be appropriately selected according to the type of tea leaves and the characteristics of the target tea beverage product. After extracting the tea leaves, the tea leaves and the liquid are separated and cooled. Next, the liquid is filtered to obtain a clear tea extract. This tea extract may be optionally diluted.

  Next, the pH of the obtained tea extract is adjusted to a range of 5.0 to 6.0, preferably 5.3 to 5.8. When mixing nitrogen in the subsequent process, liquid color browning and generation of deteriorated odor occur at pH 6.0 or higher, and odor called potato odor occurs at pH less than 5.0, which may further cause cream down There is. According to the method of the present invention, the deterioration of flavor properties can be prevented by adjusting the pH to the range of 5.0 to 6.0. By making it preferably in the range of 5.3 to 5.8, the deterioration of flavor properties can be further prevented to a minimum. The pH may be adjusted using a known appropriate additive, for example, ascorbic acid, sodium bicarbonate, etc., but is not limited thereto.

  Next, nitrogen is mixed with the tea extract whose pH is adjusted. Nitrogen may be mixed according to a well-known method, for example, gas replacement. Next, after mixing nitrogen, a negative pressure of 0.01 MPa or more is immediately applied. That is, a negative differential pressure of 0.01 MPa or more is generated. By applying a negative differential pressure of 0.01 MPa or more, the mixing and dispersion of nitrogen is promoted, nitrogen can be stably dispersed in the solution, and the oxygen concentration can be efficiently reduced. Further, the degree to which the negative pressure is applied is not particularly limited as long as it is 0.01 MPa or more, but from the viewpoint of foaming, it is limited to 1 MPa, and more preferably 0.5 MPa or less.

  Subsequently, the tea extract is brought to a pressure equal to or lower than atmospheric pressure, and is stabilized for 30 seconds to 20 minutes, preferably 30 seconds to 10 minutes. By maintaining the pressure below atmospheric pressure, oxygen and nitrogen remaining in the solution are foamed out of the solution, and the nitrogen mixed solution is stabilized. Thereby, generation | occurrence | production of the variation in dissolved oxygen concentration and pH in the manufactured tea drink can be reduced. At this time, if the stabilization time is too long, re-dissolution of oxygen may occur. If it is kept for 10 minutes or less, it is possible to suppress re-dissolution of oxygen more effectively.

  Further, the pH of the stabilized tea extract is adjusted again. In pH adjustment in this process, it is good to adjust to the range of pH5.5-6.5 from a viewpoint of suppressing deterioration of a flavor and a color tone. Preferably, by adjusting the pH to 5.8 to 6.3, it is possible to minimize the deterioration of flavor and color tone due to the subsequent sterilization process.

  The tea extract prepared by the above steps usually has a dissolved oxygen content of 1 ppm or less. The tea extract thus obtained can be subsequently heat sterilized, filled in a sealed container and provided as a tea beverage product.

  As described above, by following the method of the present invention, the dissolved oxygen concentration of the tea extract can be stably reduced, and the oxidative deterioration due to nitrogen mixing and heat sterilization can be reliably suppressed. Therefore, it is possible to stably provide a tea beverage that retains the original flavor of tea that is excellent in flavor and light blue.

  The tea beverage produced according to the method of the present invention may be filled in any sealed container such as PET, bottles, cans, paper packs and the like, and particularly preferably filled in high barrier PET. It is not limited to. Here, the high barrier PET means PET in which the amount of permeated oxygen is reduced by making the resin into a multilayer or inserting a material capable of absorbing oxygen, and has a smaller amount of oxygen permeation than normal PET. Any one may be used.

  Next, a tea beverage was prepared according to the method of the present invention and sensory evaluation was performed. The methods for preparing the tea beverages of each Example and Comparative Example are shown in detail below.

[Example 1]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 5.7 using sodium bicarbonate was obtained.
After this mixed solution was mixed with nitrogen by a gas replacement method, a negative pressure of 0.04 MPa was applied, and then kept at atmospheric pressure for 7 minutes to stabilize and correct the pH to 6.2 with ascorbic acid. The dissolved oxygen concentration at this time was 0.2 ppm.
Thereafter, it was sterilized at 136 ° C. for 30 seconds and filled into a PET bottle to obtain a container-packed green tea beverage.

[Example 2]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 5.6 using sodium bicarbonate was obtained.
After this mixed solution was mixed with nitrogen by a gas replacement method, a negative pressure of 0.03 MPa was applied, and then kept at atmospheric pressure for 1 minute to stabilize and the pH was corrected to 6.1 with ascorbic acid. The dissolved oxygen concentration at this time was 0.3 ppm.
Thereafter, it was sterilized at 136 ° C. for 30 seconds and filled into a PET bottle to obtain a container-packed green tea beverage.

[Example 3]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 5.7 using sodium bicarbonate was obtained.
After this mixed solution was mixed with nitrogen by a gas replacement method, a negative pressure of 0.04 MPa was applied, and subsequently maintained at atmospheric pressure for 2 minutes to stabilize, and then the pH was corrected to 6.2 with ascorbic acid. The dissolved oxygen concentration at this time was 0.3 ppm.
Thereafter, it was sterilized at 136 ° C. for 30 seconds and filled in a sterilized PET bottle under aseptic conditions to obtain a container-packed green tea beverage.

[Example 4]
Sterilization was performed by the method of Example 1, filled into a high barrier bottle (Aktis bottle manufactured by Hokkai Seikan Co., Ltd.) to obtain a container-packed green tea beverage.

[Comparative Example 1]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 6.3 using sodium bicarbonate was obtained. The dissolved oxygen concentration at this time was 7.2 ppm.
After this mixed solution was mixed with nitrogen by a gas replacement method, a negative pressure of 0.05 MPa was applied, and then maintained at atmospheric pressure for 3 minutes. The dissolved oxygen concentration at this time was 0.3 ppm.
Thereafter, it was sterilized at 136 ° C. for 30 seconds and filled into a PET bottle to obtain a container-packed green tea beverage.

[Comparative Example 2]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 4.6 using sodium bicarbonate was obtained. The dissolved oxygen concentration at this time was 7.5 ppm.
After this mixed solution was mixed with nitrogen by a gas replacement method, a negative pressure of 0.05 MPa was applied, and then maintained at atmospheric pressure for 3 minutes. The dissolved oxygen concentration at this time was 0.3 ppm.

  Thereafter, it was sterilized at 136 ° C. for 30 seconds and filled into a PET bottle to obtain a container-packed green tea beverage.

[Comparative Example 3]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 6.2 using sodium bicarbonate was obtained. The dissolved oxygen concentration at this time was 7.6 ppm.
Thereafter, it was sterilized at 136 ° C. for 30 seconds and filled into a PET bottle to obtain a container-packed green tea beverage.

[Comparative Example 4]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 5.7 using sodium bicarbonate was obtained. The dissolved oxygen concentration at this time was 7.6 ppm.
After this mixed solution was mixed with nitrogen by a gas replacement method, it was kept at atmospheric pressure for 4 minutes for stabilization, and the pH was corrected to 6.1 with ascorbic acid. The dissolved oxygen concentration at this time was 1.8 ppm.
Thereafter, it was sterilized at 136 ° C. for 30 seconds and filled into a PET bottle to obtain a container-packed green tea beverage.

[Comparative Example 5]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 5.7 using sodium bicarbonate was obtained. The dissolved oxygen concentration at this time was 7.6 ppm.
This mixed solution was mixed with nitrogen by a gas replacement method, then a negative pressure of 0.04 MPa was applied, sterilized at 136 ° C. for 30 seconds without being kept under atmospheric pressure, filled into a PET bottle and made into a container-packed green tea beverage .

[Comparative Example 6]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 5.6 using sodium bicarbonate was obtained. The dissolved oxygen concentration at this time was 7.8 ppm.
This mixed solution was mixed with nitrogen by a gas replacement method, and then a negative pressure of 0.05 MPa was applied. Subsequently, the mixture was maintained at atmospheric pressure for 30 minutes for stabilization, and the pH was corrected to 6.2 with ascorbic acid. The dissolved oxygen concentration at this time was 1.7 ppm.
Thereafter, it was sterilized at 136 ° C. for 30 seconds and filled into a PET bottle to obtain a container-packed green tea beverage.

[Comparative Example 7]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution with pH adjusted to 5.8 using sodium bicarbonate was obtained. The dissolved oxygen concentration at this time was 7.6 ppm.
This mixed solution was mixed with nitrogen by a gas replacement method, sterilized at 136 ° C. for 30 seconds, and filled into a PET bottle to obtain a container-packed green tea beverage.

[Comparative Example 8]
After extracting 100 g of green tea leaves at 85 ° C. for 4 minutes, the tea leaves were separated and cooled to 25 ° C. and then clarified by filtration. To this extract, 3 g of ascorbic acid (BASF Takeda Vitamin Co., Ltd.) was added, and 10 kg of a prepared solution adjusted to pH 6.0 with sodium bicarbonate was obtained. The dissolved oxygen concentration at this time was 7.4 ppm.
This prepared solution was deaerated by a vacuum deaeration method to reduce the dissolved oxygen concentration to 3.6 ppm, sterilized at 136 ° C. for 30 seconds, filled into a PET bottle, and made into a container-packed green tea beverage.

[result]
The green tea beverages of Examples and Comparative Examples were subjected to sensory evaluation immediately after production and after storage at 37 ° C. for 2 weeks. Evaluation of the tea beverage immediately after production was referred to as primary evaluation, and evaluation of the tea beverage stored at 37 ° C. for 2 weeks was referred to as secondary evaluation. The results are shown in Table 1. The sensory evaluation was performed by five skilled examiners, and the evaluation criteria are as follows: Good: 4 points, slightly good: 3 points, slightly bad: 2 points, bad: 1 point. In addition, as a comprehensive evaluation, the average score of five people was described as follows: ◎: 3.5 or more, ○: 2.5 or more, △: 1.5 or more and less than 2.5, ×: less than 1.5.

In Comparative Example 1, the taste was light white and particularly light blue browning occurred. Moreover, the comparative example 2 produced the potato-like aroma. In both Comparative Examples 1 and 2, it was shown that the pH is outside the appropriate range according to the present invention, and therefore the flavor is affected by insufficient pH adjustment.
In Comparative Example 3, the fragrance was weak, and the taste-deteriorating odor and light blue browning were observed. This is considered due to the fact that nitrogen mixing was not performed. Although the comparative example 4 performed nitrogen mixing, since the process of applying a negative pressure was not performed, it was shown that nitrogen substitution is inadequate.
In Comparative Example 5 in which the stabilization process was not performed, the fragrance was weak and the light blue color turned brown. Moreover, although the comparative example 7 performed nitrogen mixing, the process of adding a negative pressure and the stabilization process were not performed. In Comparative Example 7, the fragrance was weak and light blue browning occurred. On the other hand, Example 3 under substantially the same conditions was excellent in both fragrance and light blue color, and it was shown that nitrogen substitution was efficiently performed by the negative pressure / stabilization process.
In Comparative Example 6, both the aroma and light blue were slightly deteriorated, and it is considered that re-dissolution of oxygen occurred because the stabilization process was long.

In Comparative Example 8, the deaeration operation was performed, but the evaluation of the scent was extremely low, and it was shown that the scent was removed by the deaeration operation.
On the other hand, good results were obtained in Examples 1, 2, 3, and 4 in which nitrogen was mixed in accordance with the present invention, and then the negative pressure was applied, the stabilization step, and the pH adjusted. In Example 4, the use of the high barrier bottle showed a remarkable effect in the secondary evaluation and was particularly good.

Claims (6)

Extracting tea leaves and adjusting the resulting tea extract to pH 5.0-6.0;
Mixing the tea extract with nitrogen and further applying a negative pressure of 0.01 MPa or more;
Following the step of applying the negative pressure, maintaining the tea extract at a pressure below atmospheric pressure for 30 seconds to 20 minutes to stabilize,
Adjusting the tea extract to pH 5.5-6.5 during or after the stabilization step;
A method for producing a tea beverage, comprising:   The method for producing a tea beverage according to claim 1, wherein the tea extract whose pH is adjusted after the stabilizing step has a dissolved oxygen content of 1 ppm or less.   The method for producing a tea beverage according to claim 1 or 2, wherein the stabilization step is performed under atmospheric pressure.   The method for producing a tea beverage according to any one of claims 1 to 3, further comprising a step of sterilizing the tea beverage and filling a sealed container.   The method for producing a tea beverage according to claim 4, wherein the step of filling the sealed container is performed under aseptic conditions. The said sealed container is a manufacturing method of the tea drink as described in any one of Claims 1-5 which is high barrier PET.